fix(site-finder): handle 202 on-demand geometry in analyze + error boundaries (#1001)

Critical demo-blocker: POST /analyze returns 202 {status:fetching} for parcels
whose geometry isn't cached yet (#93 on-demand НСПД fetch). useParcelAnalyzeQuery
treated 202 as success → the stub (no score/competitors) reached render → Section 3/4
threw TypeError → white screen (no error boundary). Repro confirmed on prod.

- useParcelAnalyzeQuery: 202-aware — poll /fetch-status (2s, 2-min cap), re-POST
  on ready (status-checked, no stub on 202 race), throw HTTPError on
  not_in_nspd/failed/invalid_format; horizon preserved in both POSTs; retry: false
- error boundaries: app/site-finder/analysis/[cad]/error.tsx + app/error.tsx —
  no white screen ever; calm RU message in prod, error detail in dev
- Section3/Section4: guard competitors/score against partial payloads
- CadInput: drop hardcoded default cad (empty + placeholder), raw hex → tokens

Map parcel-select already fixed by 3cea915. Part of EPIC #958.

frontend/src/app/error.tsx

@@ -0,0 +1,85 @@
+"use client";
+
+import Link from "next/link";
+
+/**
+ * App-level error boundary — global net of last resort (#1001, 958-B5).
+ *
+ * Catches render errors not handled by a nested route `error.tsx`, so no route
+ * in the app can fall through to a blank white screen.
+ */
+export default function Error({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string };
+  reset: () => void;
+}) {
+  return (
+    <main style={{ padding: "24px 20px", maxWidth: 1400, margin: "0 auto" }}>
+      <div
+        style={{
+          marginTop: 24,
+          background: "var(--bg-card, #FFFFFF)",
+          border: "1px solid var(--border-card, #E6E8EC)",
+          borderRadius: 12,
+          padding: "24px",
+        }}
+      >
+        <h1
+          style={{
+            margin: 0,
+            fontSize: 18,
+            fontWeight: 600,
+            color: "var(--fg-primary, #111111)",
+          }}
+        >
+          Что-то пошло не так
+        </h1>
+        <p
+          style={{
+            margin: "12px 0 0",
+            fontSize: 13,
+            color: "var(--fg-secondary, #5B6066)",
+          }}
+        >
+          {process.env.NODE_ENV === "production"
+            ? "Попробуйте обновить страницу или вернуться на главную."
+            : error.message || "Произошла непредвиденная ошибка."}
+        </p>
+        <div style={{ display: "flex", gap: 12, marginTop: 24 }}>
+          <button
+            type="button"
+            onClick={reset}
+            style={{
+              padding: "8px 18px",
+              fontSize: 14,
+              fontWeight: 600,
+              background: "var(--accent, #1D4ED8)",
+              color: "var(--fg-on-dark, #E2E8F0)",
+              border: "none",
+              borderRadius: 8,
+              cursor: "pointer",
+            }}
+          >
+            Повторить
+          </button>
+          <Link
+            href="/"
+            style={{
+              display: "inline-flex",
+              alignItems: "center",
+              padding: "8px 18px",
+              fontSize: 14,
+              fontWeight: 500,
+              color: "var(--accent, #1D4ED8)",
+              textDecoration: "none",
+            }}
+          >
+            ← На главную
+          </Link>
+        </div>
+      </div>
+    </main>
+  );
+}

frontend/src/app/site-finder/analysis/[cad]/error.tsx

@@ -0,0 +1,87 @@
+"use client";
+
+import Link from "next/link";
+
+/**
+ * Route-level error boundary for the Site Finder analysis page (#1001, 958-B5).
+ *
+ * Net of last resort: even if an unforeseen payload (e.g. a 202 stub missing
+ * `score`/`competitors`) slips past the query/section guards and throws during
+ * render, the App Router catches it here and shows a graceful card instead of
+ * a blank white screen.
+ */
+export default function Error({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string };
+  reset: () => void;
+}) {
+  return (
+    <main style={{ padding: "24px 20px", maxWidth: 1400, margin: "0 auto" }}>
+      <div
+        style={{
+          marginTop: 24,
+          background: "var(--bg-card, #FFFFFF)",
+          border: "1px solid var(--border-card, #E6E8EC)",
+          borderRadius: 12,
+          padding: "24px",
+        }}
+      >
+        <h1
+          style={{
+            margin: 0,
+            fontSize: 18,
+            fontWeight: 600,
+            color: "var(--fg-primary, #111111)",
+          }}
+        >
+          Не удалось отобразить анализ участка
+        </h1>
+        <p
+          style={{
+            margin: "12px 0 0",
+            fontSize: 13,
+            color: "var(--fg-secondary, #5B6066)",
+          }}
+        >
+          {process.env.NODE_ENV === "production"
+            ? "Попробуйте обновить страницу или вернуться к выбору участка."
+            : error.message || "Произошла непредвиденная ошибка при отрисовке."}
+        </p>
+        <div style={{ display: "flex", gap: 12, marginTop: 24 }}>
+          <button
+            type="button"
+            onClick={reset}
+            style={{
+              padding: "8px 18px",
+              fontSize: 14,
+              fontWeight: 600,
+              background: "var(--accent, #1D4ED8)",
+              color: "var(--fg-on-dark, #E2E8F0)",
+              border: "none",
+              borderRadius: 8,
+              cursor: "pointer",
+            }}
+          >
+            Повторить
+          </button>
+          <Link
+            href="/site-finder"
+            style={{
+              display: "inline-flex",
+              alignItems: "center",
+              padding: "8px 18px",
+              fontSize: 14,
+              fontWeight: 500,
+              color: "var(--accent, #1D4ED8)",
+              textDecoration: "none",
+            }}
+          >
+            ← Site Finder
+          </Link>
+        </div>
+      </div>
+    </main>
+  );
+}

frontend/src/components/site-finder/CadInput.tsx

@@ -13,7 +13,7 @@ interface Props {
 }
 
 export function CadInput({ onSubmit, loading }: Props) {
-  const [value, setValue] = useState("66:41:0204016:10");
+  const [value, setValue] = useState("");
   const [error, setError] = useState<string | null>(null);
 
   function handleSubmit(e: React.FormEvent) {
@@ -56,7 +56,9 @@ export function CadInput({ onSubmit, loading }: Props) {
             flex: 1,
             padding: "8px 12px",
             fontSize: 14,
-            border: error ? "1px solid #ef4444" : "1px solid #d1d5db",
+            border: error
+              ? "1px solid var(--danger, #B3261E)"
+              : "1px solid var(--border-strong, #D1D5DB)",
             borderRadius: 8,
             outline: "none",
             fontFamily: "monospace",
@@ -70,8 +72,10 @@ export function CadInput({ onSubmit, loading }: Props) {
             padding: "8px 18px",
             fontSize: 14,
             fontWeight: 600,
-            background: loading ? "#9ca3af" : "#1d4ed8",
-            color: "#fff",
+            background: loading
+              ? "var(--fg-tertiary, #73767E)"
+              : "var(--accent, #1D4ED8)",
+            color: "var(--fg-on-dark, #E2E8F0)",
             border: "none",
             borderRadius: 8,
             cursor: loading ? "default" : "pointer",
@@ -82,9 +86,23 @@ export function CadInput({ onSubmit, loading }: Props) {
         </button>
       </div>
       {error && (
-        <p style={{ marginTop: 6, fontSize: 12, color: "#ef4444" }}>{error}</p>
+        <p
+          style={{
+            marginTop: 8,
+            fontSize: 12,
+            color: "var(--danger, #B3261E)",
+          }}
+        >
+          {error}
+        </p>
       )}
-      <p style={{ marginTop: 4, fontSize: 11, color: "#9ca3af" }}>
+      <p
+        style={{
+          marginTop: 4,
+          fontSize: 11,
+          color: "var(--fg-tertiary, #73767E)",
+        }}
+      >
         Примеры: <code>66:41:0204016:10</code> (участок) ·{" "}
         <code>66:41:0204016</code> (квартал)
       </p>

frontend/src/components/site-finder/analysis/Section3SettingsAndCompetitors.tsx

@@ -605,7 +605,9 @@ function applyFilters(
   data: ParcelAnalysis,
   filters: FilterState,
 ): ParcelAnalysis["competitors"] {
-  let result = [...data.competitors];
+  // Guard: a 202 on-demand-fetch stub (#1001) or older backend may omit the
+  // array entirely — fall back to empty so we render an empty state, not throw.
+  let result = [...(data.competitors ?? [])];
 
   // Radius filter — distance_m is in metres from the parcel centroid
   result = result.filter((c) => c.distance_m <= filters.radiusKm * 1000);
@@ -631,6 +633,8 @@ export function Section3SettingsAndCompetitors({ cad, data }: Props) {
     useState<ParcelAnalysisCompetitor | null>(null);
 
   const filteredCompetitors = applyFilters(data, filters);
+  // Normalise once — a 202 stub / older backend may omit `competitors` (#1001).
+  const competitorCount = (data.competitors ?? []).length;
   const districtName = data.district?.district_name ?? null;
 
   return (
@@ -660,8 +664,8 @@ export function Section3SettingsAndCompetitors({ cad, data }: Props) {
             color: "var(--fg-on-dark-muted, #94A3B8)",
           }}
         >
-          {data.competitors.length > 0
-            ? `${filteredCompetitors.length} из ${data.competitors.length} объектов в радиусе ${filters.radiusKm} км`
+          {competitorCount > 0
+            ? `${filteredCompetitors.length} из ${competitorCount} объектов в радиусе ${filters.radiusKm} км`
             : "Конкуренты не найдены в радиусе анализа"}
         </div>
       </div>
@@ -684,8 +688,8 @@ export function Section3SettingsAndCompetitors({ cad, data }: Props) {
       </div>
 
       {/* Filtered competitors count hint */}
-      {data.competitors.length > 0 &&
-        filteredCompetitors.length !== data.competitors.length && (
+      {competitorCount > 0 &&
+        filteredCompetitors.length !== competitorCount && (
           <div
             style={{
               marginTop: 16,
@@ -697,7 +701,7 @@ export function Section3SettingsAndCompetitors({ cad, data }: Props) {
             }}
           >
             Фильтр по радиусу: показано {filteredCompetitors.length} из{" "}
-            {data.competitors.length} конкурентов
+            {competitorCount} конкурентов
           </div>
         )}
 

frontend/src/components/site-finder/analysis/Section4Estimate.tsx

@@ -39,7 +39,12 @@ interface Props {
 // ── Helpers ───────────────────────────────────────────────────────────────────
 
 function buildHeadlineTitle(analysis: ParcelAnalysis): string {
-  const score = analysis.score.toFixed(1);
+  // Guard: a 202 on-demand-fetch stub (#1001) has no `score` — render "—"
+  // instead of throwing on `.toFixed` against undefined.
+  const score =
+    typeof analysis.score === "number" && Number.isFinite(analysis.score)
+      ? analysis.score.toFixed(1)
+      : "—";
   const label = analysis.score_label ?? "";
   if (label) {
     return `Оценка: ${score} · ${label.toUpperCase()}`;

frontend/src/lib/site-finder-api.ts

@@ -9,7 +9,11 @@
  */
 
 import { keepPreviousData, useQuery } from "@tanstack/react-query";
-import { apiFetch, apiFetchWithStatus } from "@/lib/api";
+import { HTTPError, apiFetch, apiFetchWithStatus } from "@/lib/api";
+import type {
+  AnalyzeAcceptedResponse,
+  FetchStatusResponse,
+} from "@/hooks/useSiteAnalysis";
 import {
   MOCK_PARCELS_BBOX,
   MOCK_RECENT_PARCELS,
@@ -326,6 +330,13 @@ export interface PoiScoreResponse {
 
 // ── Hook: useParcelAnalyzeQuery (B5) ─────────────────────────────────────────
 
+// #93 on-demand NSPD fetch: POST /analyze returns 202 for any parcel whose
+// geometry isn't cached yet. We must poll /fetch-status and re-POST once ready,
+// mirroring useSiteAnalysis — otherwise the 202 stub (no score/competitors)
+// reaches the render tree and crashes Section 3/4 (#1001, 958-B5).
+const ANALYZE_POLL_INTERVAL_MS = 2000;
+const ANALYZE_POLL_MAX_ITERATIONS = 60; // 60 × 2s = 2 min hard cap
+
 export function useParcelAnalyzeQuery(cad: string, horizon: number = 12) {
   return useQuery({
     queryKey: ["parcel-analyze", cad, horizon],
@@ -334,14 +345,77 @@ export function useParcelAnalyzeQuery(cad: string, horizon: number = 12) {
         // Return fixture data regardless of cad/horizon — for dev only
         return fixtureAnalyze as ParcelAnalyzeResponse;
       }
+
       // Backend accepts ?horizon= ∈ {6,12,18} (default 12; 422 otherwise, #995).
-      return apiFetch<ParcelAnalyzeResponse>(
-        `/api/v1/parcels/${encodeURIComponent(cad)}/analyze?horizon=${horizon}`,
-        { method: "POST" },
-      );
+      const analyzeUrl = `/api/v1/parcels/${encodeURIComponent(
+        cad,
+      )}/analyze?horizon=${horizon}`;
+
+      // First request — POST /analyze. apiFetchWithStatus surfaces the 202
+      // Accepted code instead of treating it as a successful payload.
+      const first = await apiFetchWithStatus<
+        ParcelAnalyzeResponse | AnalyzeAcceptedResponse
+      >(analyzeUrl, { method: "POST" });
+
+      // 200 → geometry was cached, full analysis is ready.
+      if (first.status === 200) {
+        return first.body as ParcelAnalyzeResponse;
+      }
+
+      // 202 Accepted → geometry is being fetched from НСПД. Poll /fetch-status
+      // every 2s; once ready re-POST /analyze (now 200). The query stays
+      // pending throughout, so the page's "Анализируем участок…" screen shows.
+      if (first.status === 202) {
+        for (let i = 0; i < ANALYZE_POLL_MAX_ITERATIONS; i++) {
+          await new Promise((r) => setTimeout(r, ANALYZE_POLL_INTERVAL_MS));
+          const status = await apiFetch<FetchStatusResponse>(
+            `/api/v1/parcels/${encodeURIComponent(cad)}/fetch-status`,
+          );
+          if (status.status === "ready") {
+            // Re-POST should now be 200. If it races back to 202, keep polling
+            // rather than returning the stub (symmetry with the first request).
+            const second = await apiFetchWithStatus<
+              ParcelAnalyzeResponse | AnalyzeAcceptedResponse
+            >(analyzeUrl, { method: "POST" });
+            if (second.status === 200) {
+              return second.body as ParcelAnalyzeResponse;
+            }
+            // 202 race → fall through and poll /fetch-status again.
+          }
+          if (status.status === "not_in_nspd") {
+            throw new HTTPError(
+              404,
+              status,
+              status.error_msg ?? "Кадастровый номер не найден в НСПД",
+            );
+          }
+          if (status.status === "failed") {
+            throw new HTTPError(
+              503,
+              status,
+              status.error_msg ?? "НСПД временно недоступен",
+            );
+          }
+          if (status.status === "invalid_format") {
+            throw new HTTPError(
+              400,
+              status,
+              status.error_msg ?? "Неверный формат кадастрового номера",
+            );
+          }
+          // status === "fetching" → continue polling
+        }
+        throw new Error(
+          "Загрузка длится слишком долго (>2 мин). Попробуйте позже.",
+        );
+      }
+
+      throw new Error(`Неожиданный статус ответа: ${first.status}`);
     },
     staleTime: 5 * 60_000, // 5 min — analyze is expensive
-    retry: 1,
+    // The queryFn polls internally; a thrown terminal error (404/503/400/
+    // timeout) is final and must NOT restart the whole poll loop via retry.
+    retry: false,
     // Horizon is in the queryKey, so switching it is a fresh cache entry. Keep
     // the previous analysis on screen while the new horizon re-fetches instead
     // of blanking the whole page to the loading state on every selector change.